The expeditious fabrication of semiconductor devices requires an extremely clean environment and high throughput. Various chambers are utilized during such fabrication for depositing materials on substrates and for annealing, or heating, and otherwise treating the in-process devices. Fabrication steps effected in such chambers may produce particulates that adhere to the interior surfaces of the chambers. The particulates may subsequently become dislodged from the interior surfaces and fall onto the in-process devices, thereby introducing undesirable impurities into the in-process devices.
Because of high throughput requirements, it is deemed undesirable to clean the chambers to remove adherent particulates after each fabrication step carried out therein. Such cleaning after each use of the chambers would slow down fabrication flow.
Most fabrication chambers contain controlled environments during the processing of semiconductor devices therewithin. These environments may include extremely low pressures, particular gases, and high temperatures. Typically, the chambers are closed by sealing an opening thereinto with a door before processing is initiated. The motive power for opening and closing the door may be derived from the operation of a linear fluid motor.
The opening and closing of a processing chamber door by a fluid linear motor has been identified as a source of particulate contamination of in-process devices within the chamber. Specifically, if the velocity of a piston of the motor that is connected to the door is too high at either end of its stroke—when the door is fully closed or opened—the high kinetic energy of the piston-door combination may vibrate the chamber, dislodging the potentially damaging particulates from the chamber surfaces. The velocity of the motor piston and the door may be slowed throughout movement thereof to minimize their combined kinetic energy and particulate dislodgement, but this expedient adversely affects throughput. The velocity of the piston-door may also be monitored and controlled by sensors and a control system, but this expedient adds expense to the fabrication equipment and requires constant maintenance and adjustment.
A simple, low cost solution to the foregoing is a desideratum of the present invention.